C

Coulometry

Q = ∫I dt; n = Q/(nF)
Quick Reference
Formula / NotationQ = ∫I dt; n = Q/(nF)
Also Known AsCoulometric analysis, controlled-potential coulometry, constant-current coulometry

What is Coulometry?

Coulometry is an electroanalytical method that measures the quantity of charge (in coulombs) required to completely convert an analyte from one oxidation state to another. Using Faraday's law, the number of moles of analyte can be calculated from the charge. Coulometry can be performed at constant potential (potentiostatic) or constant current (galvanostatic).

Formula & Notation

Q = ∫I dt; n = Q/(nF)

Other Names / Synonyms: Coulometric analysis, controlled-potential coulometry, constant-current coulometry

Properties & Characteristics

Coulometry is an electroanalytical technique that determines the amount of a substance by measuring the total charge (in coulombs) passed during a controlled electrolysis. Primary coulometry (controlled potential, 100% current efficiency at known oxidation state) or secondary (constant current Karl Fischer coulometric titration for water). Faraday's law: n = Q/(nF) gives moles converted with excellent accuracy.

Uses & Applications

Coulometry is used in Karl Fischer water determination (trace moisture analysis in pharmaceuticals and petroleum), in coulometric standardisation of reagent solutions, in pollution monitoring (oxygen demand), and in corrosion measurement. It provides a primary analytical standard without needing calibration solutions.

Safety Information

Coulometric cells may use toxic reagents (Karl Fischer reagent contains iodine, SO₂, pyridine — all irritants or toxic). Generated gases (H₂, Cl₂) must be vented appropriately. High-current coulometric systems present electrical hazards.

Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.

Key Facts

Term Coulometry
Formula Q = ∫I dt; n = Q/(nF)
Synonyms Coulometric analysis, controlled-potential coulometry, constant-current coulometry

Frequently Asked Questions

Coulometry is an electroanalytical method that measures the quantity of charge (in coulombs) required to completely convert an analyte from one oxidation state to another. Using Faraday's law, the number of moles of analyte can be calculated from the charge. Coulometry can be performed at constant potential (potentiostatic) or constant current (galvanostatic).

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